This invention relates to hand operable brake mechanisms and particularly, to a handbrake load limiter for railway cars.
Railway car handbrake mechanisms are well known and may include a rotatable wheel or lever that provides upward tension on a chain that is secured at its distal end to a brake rigging of the railway car. Sufficient force must be applied on the brake shoes of the railway car to releasably secure the wheels in a locked position to prevent the railway car from moving. An under applied brake can result in unwanted movement of the car, for example a runaway car. On the opposite end of the spectrum, an over applied brake may result in damage or failure to the brake rigging.
Previously, it has been industry standard to apply 125 pounds of force to the end of the brake lever or 125 pounds of torque force on a wheel to properly apply the handbrake. Currently, certain segments of the railway industry have lowered the 125 pound requirement to 74 pounds. This lowered threshold can result in many more instances when the handbrake is over applied. When the brake is to be fully applied with 125 pounds, there exists the possibility of the handbrake being under applied. Thus, a mechanism is needed that alerts the operator when the brake is properly applied to within a predetermined range and prevents the application of excessive input force.